Marblewood security force were the private security of the Marblewood Estate on the planet Wukkar, working for the Black Sun sector chief, Avrak Villachor. They were led by Lapis Sheqoa, a former Imperial shock trooper.
In 0 BBY, it provided security during the Festival of Four Honorings, an event which was hosted by Villachor at his estate in Iltarr City, on Wukkar. Han Solo and a crew he put together for a heist took advantage of the event and planned out a heist, during which the security force was involved in fighting them. Villachor, and the visiting Black Sun vigo Qazadi, did not trust the force fully because several members were approached by a member of Solo's crew with bribes (which they did purposely to cause distrust among them).
During the heist, several guards were killed. Qazadi was killed during it as well, and afterwards, Villachor agreed to cooperate with the Galactic Empire and give them information on the Black Sun. The fate of the security force and its members after that was unknown.